Colorectal Cancer

Question 1

What is the function of the Colon?

Answer 1

1. Extraction of water from faeces
2. Faecal reservoir
3. Bacterial digestion for vitamins (Vitamin B/K)

Question 2

What is the basic normal anatomy of the Colon?

Answer 2

1. Simple columnar epithelium that has extensive microvilli on their surface
2. Organised into villi – small projections out into the membrane
3. Goblet cells secreting mucin
4. Regenerative crypts of lieberkuhn found at the base of the villus which generates cells to replace the enterocytes that are shed

Question 3

What are the mutation that can predispose you Adenoma-carcinoma sequence (which causes which)

Answer 3

1. Germline mutation of APC / MSH2
2. Somatic mutation of APC / Beta-catenin
3. Somatic mutation of K-Ras
   
   • Adenoma
4. Additional loss of p53
   
   • Carcinoma

Question 4

What is the Clinical Presentation of Bowel Cancer?

Answer 4

1. Change in bowel habit
2. Bleeding PR
3. Unexplained iron deficiency anaemia
4. Other changes
   
   • Mucus PR
   • Bloating
   • Cramps
   • Weight loss

Question 5

Which patients do we screen? What are the different options if certain age groups turn out positive?

Answer 5

• Screen patients who are high risk
  
  1. Have had previous adenoma
  2. Previous affected first degree relatives
  3. UC / CD
  4. Evidence of familial cancer
• Checking for microscopic PR bleeding
• Positive at 60-75 years
  
  • Colonoscopy
• Positive at 55-60 years
  
  • Sigmoidoscopy

Question 6

What staging method is used in Colorectal Cancer?

Answer 6

Dukes staging

A

• Limited to wall, nodes negative

B

• Growth beyond muscularis mucosa
• No nodes

C1

• Node positive
• Apical lymph node negative

C2

• Apical lymph node positive